1 . Field of the Invention
The present invention generally relates to a transceiver device, in particular, to an impedance matching technique of the transceiver device.
2 . Description of Related Art
In a communication system, usually a transceiver is used to transmit signals. The transceiver is composed of a transmitter (TX) and a receiver (RX). FIG. 1 is a schematic view of a conventional full duplex transceiver. Referring to FIG. 1, a near-end transceiver 102 and a far-end transceiver 104 are full duplex transceivers, that is, the near-end transceiver 102 and the far-end transceiver 104 may perform a bidirectional data transmission through a transmission line 114 at the same time. The near-end transceiver 102 includes a TX 106, an RX 108, and a hybrid circuit 116, and the far-end transceiver 104 includes a TX 110, an RX 112, and a hybrid circuit 118.
From the perspective of the near-end transceiver 102, the TX 106 may transmit the signal to the RX 112 in the far-end transceiver 104 through the transmission line 114. However, when the TX 106 in the near-end transceiver 102 transmits the signal to the far-end transceiver 104, if the impedances of the transmission line 114 and the transceivers 102 and 104 are not matched with each other, an echo signal 120 may be generated. The echo signal 120 may be transmitted back to the RX 108 in the near-end transceiver 102, and the RX 108 may consider the echo signal 120 as an interference noise.
It should be noted that the larger impedance difference of the transmission line 114 and the transceivers 102 and 104 results in the larger magnitude of the echo signal 120.